In the course of time human beings have tried lying on different supports. One problem was to place the nape of one's neck and head in a desirable manner. There may be many different manners to do that. One may try to twist one's pillow in one's sleep, bundle it up into a sphere, or fold it over, still it is very difficult to achieve a desired pillow shape. It is also possible to buy an anatomically shaped pillow.
Extreme measures also exist as regards positions of rest for a person's head or nape of the neck. An example which we may mention is a native tribe living a nomadic life in the Kalahari desert. Such a native sleeps with his head on a shoulder with the upper part of his arm serving as a supporting pillar and his elbow firmly planted in the sand. This is due to the fact that it is necessary to hold one's head above the sand to prevent small crawling animals from getting into one's ears and across one's face. They get used to this from childhood and can live with it because they lead a varied life in the daytime while they are active.
Conditions are different if someone works at an office and sits with his head and nape of the neck stooped forwards all the day and then lies with his head and the nape of his neck stooped forwards on a large pillow at night.
In a modern society of fashions and customs we get used to the present round and soft pillow from childhood. We do not enjoy this lying position as much when we sit at school all day or later, as grown-up persons with working conditions causing the normal sway-back of the nape of the neck (cervical lordosis) to be straightened. This is due to the fact that the daily strains and forms of strain change as we grow up and we feel a need for relief from special positions, even when we are asleep.
In later years pillows were manufactured which conform with the anatomic build of the nape of the neck so as to bring relief from tensions of the neck muscles. Such pillows were manufactured more or less successfully. A weakness of many of them was that they mainly supported the central portion of the back of the neck and produced a pressure forwards in order to maintain a normal lordosis of the back of the neck. When lying on one's back (supine) with gravitation acting in a downward direction, and when there is no support of any kind in the upper thoracal region, and little or no support in the region of the nape of the neck/breast/back (cervicothoracal region) a shear force will be created in this region.
The less support there is in the lower part of nape of the neck (cervical region) and in the upper part of the thoracal region, the more shear force and negative strain there will be.
Supporting pillows of an anatomical shape were produced from more or less hard and soft materials, mainly they were moulded or cut from foamed plastic or foamed rubber. Even the softest foamed material will, due to its consistency and structure tend not to stretch and conform with the shape of the body as well as a more loosely bound material, e.g. fibres. Also, the exact anatomic shape of the supporting pillow will often only feel good during the first period of lying on it. If one wants to lie in a lateral position a pillow with an anatomic shape which is formed for lying on one's back (supine) will often be of little use.
Due to the user's need of variation of strain, as opposed to the exact anatomic shape of the supporting pillow, the user will often show a "Princess on the Pea" syndrome and many users cannot manage to use it because getting numb in the nape of the neck and the shoulders due to lack of variation.
The harder the material of the supporting pillow is--with resulting distribution of the weight of one's head and nape of the neck over a smaller support area--the higher shear force and negative strain.
Most specially shaped supporting pillows are at present relatively expensive in addition to the fact that they do not always meet the requirements to correct and varied strain.